System and method for diagnosing lack of coolant of vehicle to which integrated thermal management valve is applied

ABSTRACT

A system for diagnosing lack of coolant of a vehicle to which an integrated thermal management valve is applied according to the present disclosure includes an integrated thermal management valve including a plurality of valves which are openable and closable, and configured to selectively distribute coolant introduced from a head of an engine to front ends of a radiator, a heater, and an oil cooler, a coolant temperature sensor installed on each of a coolant inlet, a coolant outlet, and a block of the engine and configured to measure a temperature of the coolant, and a control unit configured to determine whether the coolant is insufficient by monitoring a decrease amount of a coolant temperature difference measured from the block and the coolant outlet, and finally determine whether the coolant is insufficient by accumulating an increase amount of a temperature difference between the coolant outlet and the coolant inlet.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims under 35 U.S.C. § 119(a) the benefit of priority to Korean Patent Application No. 10-2022-0076516 filed on Jun. 23, 2022, the entire contents of which are incorporated herein by reference.

BACKGROUND (a) Technical Field

The present disclosure relates to a system and method for diagnosing lack of coolant of a vehicle to which an integrated thermal management valve is applied, and more specifically, to a system and method for diagnosing lack of coolant of a vehicle to which an integrated thermal management valve is applied, which may prevent damage to an internal combustion engine by recognizing a situation in which the coolant is overheated due to the lack of the coolant in advance.

(b) Background Art

In general, the simultaneous satisfaction of high fuel efficiency and high performance is a typical trade-off problem of fuel efficiency-performance of gasoline/diesel vehicles, and one method to solve this problem is, for example, to improve the performance of a vehicle thermal management system (hereinafter, referred to as “VTMS”).

This is because the VTMS is constructed to connect an engine cooling system, an exhaust gas recirculation (EGR) system, an auto transmission fluid (ATF) system, and a heater system with an engine, and may simultaneously satisfy high fuel efficiency and high performance by effectively controlling high-temperature coolant of the engine transmitted to each system to be distributed according to vehicle or engine operation conditions.

Accordingly, in the VTMS, efficiency for engine coolant distribution control is a very important design factor, and to this end, it is preferable to use an integrated thermal management valve (hereinafter, referred to as “ITM”) for coolant distribution control in order to efficiently control the plurality of thermal exchange systems at the same time. The ITM controls coolant distribution by maintaining a coolant temperature in some of the plurality of thermal exchange systems connected to the engine high, while maintaining the coolant temperature in the remaining systems low.

For example, the ITM may optimize the thermal exchange effect of the engine coolant whose temperature is changed depending on an operation state of the engine by having an inlet through which engine coolant is introduced and three ports for allowing the introduced engine coolant to be discharged in different directions and connecting the heater system in four directions by four ports.

In this case, the cooling system may be a radiator configured to decrease a temperature of engine coolant through heat exchange with the outside air, the EGR system may be an EGR cooler configured to decrease a temperature of an EGR gas transmitted to the engine among exhaust gases through heat exchange with the engine coolant, the oil cooler system may be an oil warmer configured to increase a temperature of engine oil through heat exchange with the engine coolant, and the heater system may be a heater core configured to increase a temperature of outside air through heat exchange with the engine coolant.

Furthermore, since the ITM may perform the selective opening control of the ITM using temperature detection values of coolant temperature sensors provided on coolant inlet/outlet sides of the engine for individual coolant control of the EGR cooler, the oil warmer, and the heater core, it can be more effective in decreasing fuel consumption while improving the overall cooling efficiency of the engine.

The coolant temperature sensor may be used to not only control the opening of the ITM, but also to diagnose lack of the coolant by accumulating an increase amount of temperature difference on inlet/outlet sides. However, there is a problem in that the diagnosis accuracy of lack of the coolant is inevitably lowered because the coolant temperature difference may be increased even when a high load operation is performed in which a heat-dissipation amount of the engine increases even when the coolant is not insufficient.

The above information disclosed in this Background section is only for enhancement of understanding of the background of the disclosure and accordingly it may include information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.

SUMMARY

An object of the present disclosure is to provide a system and method for diagnosing lack of coolant of a vehicle to which an integrated thermal management valve is applied, which may recognize a situation in which coolant is overheated due to lack of coolant in advance by determining the diagnosis for lack of coolant using a temperature difference between an engine block and an engine outlet detected through three coolant temperature sensors installed on the engine outlet, an engine inlet, and the engine block in order to apply variable split cooling through an integrated thermal management valve (ITM), and finally determining that the coolant is insufficient when a factor in which the difference exceeds a set value using the temperature difference between the engine outlet and the engine inlet at this time is continuously accumulated, thereby performing maintenance and check accordingly, and preventing damage to an internal combustion engine.

A system for diagnosing lack of coolant of a vehicle to which an integrated thermal management valve is applied according to the present disclosure includes an integrated thermal management valve including a plurality of valves which are openable and closable, and configured to selectively distribute coolant introduced from a head of an engine to front ends of a radiator, a heater, and an oil cooler, a coolant temperature sensor installed on each of a coolant inlet, a coolant outlet, and a block of the engine and configured to measure a temperature of the coolant, and a control unit configured to determine whether the coolant is insufficient by monitoring a decrease amount of a coolant temperature difference measured from the block and the coolant outlet, and finally determine whether the coolant is insufficient by accumulating an increase amount of a temperature difference between the coolant outlet and the coolant inlet.

Here, the control unit determines whether the coolant is insufficient as a valve on an outlet side connected to the radiator in the integrated thermal management valve is open due to an increase in the coolant temperature.

In addition, the control unit primarily determines that the coolant is insufficient when it is determined that the coolant temperature difference measured from the block and the coolant outlet is lower than or equal to a set temperature.

In addition, the control unit continuously monitors an increase amount of the temperature difference between the coolant outlet and the coolant inlet when it is primarily determined that the coolant is insufficient, and finally determines that the coolant is insufficient when it is determined that an accumulated factor value is greater than or equal to a set comparison value by accumulating different factor values for each continuous temperature difference.

Meanwhile, a method of diagnosing lack of coolant of a vehicle to which an integrated thermal management valve is applied according to the present disclosure includes a first operation of determining whether a valve on a radiator side constituting an integrated thermal management valve is open, a second operation of measuring a coolant temperature through a coolant temperature sensor installed on each of a coolant outlet and a block of an engine as the valve on the outlet side is open, and primarily determining, by a control unit, whether coolant is insufficient by monitoring a decrease amount of a coolant temperature difference, a third operation of calculating, by the control unit, an increase amount of a temperature difference between the coolant outlet and a coolant inlet when it is determined as a state in which it is primarily determined that the coolant is insufficient, and a fourth operation of accumulating the increase amount of the calculated temperature difference between the coolant outlet and the coolant inlet as a factor value by continuously performing the third operation, and finally determining, by the control unit, whether the coolant is insufficient using the accumulated factor value.

Here, in the second operation, whether an initial condition for determining whether the coolant is insufficient is satisfied is determined by measuring traveling environment information in the state in which the valve on the outlet side is open before measuring the coolant temperature through the coolant temperature sensor.

The initial condition includes RPM information of the engine, inclination information at which a vehicle is positioned, and outside air temperature information of the vehicle.

In addition, in the second operation, when it is determined that the coolant temperature difference measured from the block and the coolant outlet is lower than or equal to a set temperature, it is primarily determined that the coolant is insufficient.

In addition, in the fourth operation, when it is determined that the factor value accumulated through the third operation is greater than or equal to a set comparison value, it is finally determined that the coolant is insufficient.

In addition, the method of diagnosing lack of the coolant of the vehicle to which the integrated thermal management valve is applied according to the present disclosure further includes a fifth operation of transmitting, by the control unit, coolant lack information to a driver when it is finally determined that the coolant is insufficient in the fourth operation, and transmitting a control signal for proceeding to a fail-safe mode to the integrated thermal management valve.

According to the present disclosure, it is possible to improve accuracy in determining whether coolant is insufficient by primarily determining the diagnosis for lack of coolant using the temperature difference between the engine block and the engine outlet detected through three coolant temperature sensors installed on the engine outlet, the engine inlet, and the engine block in order to apply variable split cooling through the integrated thermal management valve (ITM), and finally determining that the coolant is insufficient when the factor in which the difference exceeds the set value using the temperature difference between the engine outlet and the engine inlet at this time is continuously accumulated.

Accordingly, according to the present disclosure, it is possible to prevent damage to the internal combustion engine by recognizing the situation in which the coolant is overheated due to lack of the coolant to transmit the situation to the driver and inducing the driver to check and repair the cooling system before being exposed to the dangerous situation due to lack of the coolant.

In addition, according to the present disclosure, it is possible to maximize the cooling efficiency of the cooling system by maximally operating the cooling fan, while opening all flow paths of the coolant, thereby easily securing the movement distance required for visiting the auto shop for solving the problem of lack of the coolant.

In addition, according to the present disclosure, it is possible to diagnose lack of the coolant using the temperature difference between the engine block and the engine outlet, thereby solving the conventional problem that lack of the coolant is determined using the coolant temperature sensors installed on the engine outlet and the engine inlet, that is, the conventional problem of occurrence of the diagnosis error that it is determined that the coolant is insufficient as the coolant temperature difference between the engine outlet and the engine inlet increases due to the increase in the heat-dissipation amount of the engine.

It is understood that the term “automotive” or “vehicular” or other similar term as used herein is inclusive of motor automotives in general such as passenger automobiles including sports utility automotives (operation SUV), buses, trucks, various commercial automotives, watercraft including a variety of boats and ships, aircraft, and the like, and includes hybrid automotives, electric automotives, plug-in hybrid electric automotives, hydrogen-powered automotives and other alternative fuel automotives (e.g., fuels derived from resources other than petroleum). As referred to herein, a hybrid automotive is an automotive that has two or more sources of power, for example both gasoline-powered and electric-powered automotives.

The above and other features of the disclosure are discussed infra.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features of the present disclosure will now be described in detail with reference to certain exemplary examples thereof illustrated in the accompanying drawings which are given herein below by way of illustration only, and thus are not limitative of the present disclosure, and wherein:

FIG. 1 is a block diagram showing a configuration of a system for diagnosing lack of coolant of a vehicle to which an integrated thermal management valve is applied according to one embodiment of the present disclosure;

FIG. 2 is a block diagram showing a configuration of a conventional system for diagnosing lack of coolant of a vehicle to which an integrated thermal management valve is applied;

FIG. 3 is a view schematically showing the system for diagnosing lack of the coolant of the vehicle to which the integrated thermal management valve is applied according to one embodiment of the present disclosure;

FIG. 4 is a view showing a system for diagnosing lack of coolant of a vehicle to which an integrated thermal management valve is applied according to another embodiment of the present disclosure; and

FIG. 5 is a view sequentially showing a method of diagnosing lack of the coolant of the vehicle to which the integrated thermal management valve is applied according to another embodiment of the present disclosure.

It should be understood that the appended drawings are not necessarily to scale, presenting a somewhat simplified representation of various preferred features illustrative of the basic principles of the disclosure. The specific design features of the present disclosure as disclosed herein, including, for example, specific dimensions, orientations, locations, and shapes will be determined in section by the particular intended application and use environment.

In the figures, reference numbers refer to the same or equivalent sections of the present disclosure throughout the several figures of the drawing.

DETAILED DESCRIPTION

Hereinafter, preferred embodiments according to the present disclosure will be described in detail with reference to the accompanying drawings.

Advantages and features of the present disclosure, and a method for achieving the same, will become apparent with reference to the embodiments to be described below in detail in conjunction with the accompanying drawings.

However, the present disclosure is not limited by the embodiments disclosed below but will be implemented in various different forms, and only these embodiments are provided so that the disclosure of the present disclosure will be thorough and complete and will fully convey the scope of the present disclosure to those skilled in the art to which the present disclosure pertains, and the present disclosure is defined by the description of the claims.

In addition, in the description of the present disclosure, when it is determined that related known techniques may obscure the gist of the present disclosure, a detailed description thereof will be omitted.

FIG. 1 is a block diagram showing a configuration of a system for diagnosing lack of coolant of a vehicle to which an integrated thermal management valve is applied, according to one embodiment of the present disclosure, and FIG. 2 is a block diagram showing a configuration of a conventional system for diagnosing lack of coolant of a vehicle to which an integrated thermal management valve is applied.

In addition, FIG. 3 is a view schematically showing the system for diagnosing lack of the coolant of the vehicle to which the integrated thermal management valve is applied according to one embodiment of the present disclosure, and FIG. 4 is a view showing a system for diagnosing lack of coolant of a vehicle to which an integrated thermal management valve is applied according to another embodiment of the present disclosure.

As shown in FIGS. 1 and 3 , a system for diagnosing lack of coolant of a vehicle to which an integrated thermal management valve is applied according to this embodiment includes an integrated thermal management valve 100, a plurality of coolant temperature sensors 200, 300, and 400, and a control unit 500.

In engines recently developed, the application of the electronically controlled integrated thermal management valve 100 is spreading in order to decrease the loss of a cooling system.

The integrated thermal management valve 100 is configured to control the flow of engine coolant according to engine conditions, and preferably, the integrated thermal management valve 100 is made of a plastic material, and is mainly applied to a split cooling method of separately cooling a head 1 a and a block 1 b in order to decrease the loss of the cooling system of an engine 1 composed of the head 1 a and the block 1 b vertically.

Here, in this embodiment, although it has been described that the integrated thermal management valve 100 is applied to apply variable split cooling, this is only an example, and in addition, the integrated thermal management valve 100 may also be applied by being replaced with a water temperature controller assembly (WTCA) which implements a variable split cooling function by applying a main mechanical thermostat and a block thermostat, and monitors a coolant temperature of the block by applying a coolant temperature sensor on the block side in addition to a coolant temperature sensor on an engine outlet.

The integrated thermal management valve 100 includes a plurality of valves 100 a, 100 b, and 100 c which may be opened and closed, and is formed to selectively distribute the coolant introduced from the head 1 a to a front end of a water pump P through a radiator 2, a heater 3, and an oil cooler 4.

The plurality of coolant temperature sensors 200, 300, and 400 are provided, and more specifically, are provided as the coolant temperature sensor 200 installed on a coolant inlet of the engine 1, the coolant temperature sensor 300 installed on a coolant outlet of the engine 1, and the coolant temperature sensor 400 installed on the block 1 b of the engine 1, and functions to measure a temperature of the coolant at each position.

Here, the control unit 500 primarily determines whether the coolant is insufficient by monitoring a decrease amount of a coolant temperature difference measured from the block 1 b and the coolant outlet through the coolant temperature sensors 300 and 400.

In other words, as shown in FIG. 2 , the conventional system diagnoses lack of coolant by accumulating an increase amount of each temperature difference measured from the coolant temperature sensor 200 installed on the coolant inlet of the engine and the coolant temperature sensor 300 installed on the coolant outlet thereof.

However, in the case of using the coolant temperature difference between the coolant inlet and the coolant outlet as described above, the temperature difference may increase even when a high load operation such as acceleration start-up is performed in which a heat-dissipation amount of the engine increases even when the coolant is not insufficient.

It can be confirmed that a coolant temperature difference ΔT increases when a heat-dissipation amount Q of the engine is increased through “heat-dissipation amount Q=specific heat C*flow rate M*coolant temperature difference ΔT,” and accordingly, when a driver performs the high load operation, the coolant may be incorrectly diagnosed as being insufficient.

Accordingly, in this embodiment, compared to the above-described conventional system, typically, when the coolant is insufficient, it is possible to accurately determine whether the coolant is insufficient through a phenomenon in which the temperature difference detected from the coolant temperature sensors 300 and 400 of the block 1 b and the engine outlet is decreased using the coolant temperature sensor 400 of the block 1 b additionally installed to apply the variable split cooling.

Specifically, when it is determined that the coolant temperature difference measured from the block 1 b and the coolant outlet is lower than or equal to a set temperature, for example, 8° C. or less, the control unit 500 primarily determines that the coolant is insufficient.

More specifically, when the coolant is insufficient, since the coolant does not smoothly flow to the radiator 2 even when the valve 100 a connected to the radiator 2 is open upon acceleration start-up, the coolant temperature on the engine coolant outlet increases, and at this time, since the coolant flow is normally stagnant on the block 1 b side, the coolant temperature on the block 1 b side is usually maintained 8° C. higher than the coolant temperature on the coolant outlet side.

Accordingly, even when the coolant of the vehicle is insufficient, since the block 1 b side is positioned below the head 1 a, there is no air included in the coolant on a flow path compared to a flow path on the head 1 a side, so that the coolant temperature may easily decrease when the valve 100 c on the block side is open upon high load operation (acceleration start-up) in a state in which the valve 100 a on the radiator side is open.

In other words, when the coolant is insufficient, referring to the above-described “Q=CMΔT”, since there is no air on the block 1 b side, a flow rate is relatively increased compared to the head 1 a, and the coolant temperature decreases relatively largely in order to preserve an amount of heat, and using this, when the coolant is insufficient, as the valve 100 c on the block side is open, the coolant temperature on the block 1 b side decreases and the coolant temperature on the head 1 a increases. Accordingly, the coolant temperature difference between the block 1 b and the coolant outlet decreases, and when the difference is repeatedly accumulated to a set temperature, that is, 8° C. or less, it may be primarily determined that the coolant is insufficient.

As described above, when the temperature difference detected by the coolant temperature sensors 300 and 400 of the block 1 b and the engine outlet decreases, using this, whether the coolant is insufficient may be accurately determined even upon high load operation (acceleration start-up), so that as shown in FIG. 4 , the coolant temperature sensor 200 of the engine inlet may also be selectively deleted as necessary.

Meanwhile, in the control of the control unit 500 for primarily determining lack of the coolant, since the determination using the temperature difference is performed in a state in which the valve 100 c on the block side is open, it is preferable to start the primary determination of whether the coolant is insufficient as the coolant temperature increases in an engine warm-up state and thus the valve 100 a on the outlet side connected to the radiator 2 is open.

Here, when it is primarily determined that the coolant is insufficient, the control unit 500 finally determines whether the coolant is insufficient by accumulating an increase amount of the temperature difference between the coolant outlet and the coolant inlet measured through the coolant temperature sensors 200 and 300.

In other words, when it is primarily determined that the coolant is insufficient, the control unit 500 continuously monitors the increase amount of the temperature difference between the coolant outlet and the coolant inlet of the engine 1, compares an accumulated factor value with a set comparison value when a plurality of different factor values for each continuous temperature difference is accumulated, and finally determines that the coolant is insufficient when it is determined that the accumulated factor value is greater than or equal to the comparison value.

For reference, the setting of the comparison value may be changed upon request, and when a quick diagnosis for lack of the coolant is desired, the comparison value may be set to a relatively smaller value.

TABLE 1 Temperature difference 0 5 10 15 20 Factor value −1 0 1 2 3

In other words, as a result of continuously monitoring the increase amount of the temperature difference between the coolant outlet and the coolant inlet in the state in which it is primarily determined that the coolant is insufficient, the temperature difference should normally be lower than 10° C., but when the temperature difference is higher than or equal to 10° C., different factor values for each temperature difference calculated as described above, for example, factor values which are 1 when the temperature difference is higher than or equal to 10° C. and 2 when the temperature difference is higher than or equal to 15° C. are accumulated as in Table 1, and at this time, the control unit 500 may finally determine that the coolant is insufficient when it is determined that the accumulated factor value is greater than or equal to the set comparison value.

As a result, in this embodiment, since it is primarily determined whether the coolant is insufficient using the temperature difference detected from the coolant temperature sensors 300 and 400 of the block 1 b and the engine outlet, it is possible to accurately diagnose lack of the coolant by solving the conventional problem that the coolant may be incorrectly diagnosed as being insufficient upon high load operation (acceleration start-up), and in addition, it is possible to improve accuracy in determining whether the coolant is insufficient by finally diagnosing that the coolant is insufficient when the difference is continuously accumulated at a specific temperature or higher using the coolant temperature difference between the engine outlet and the engine inlet.

In addition, when it is finally determined whether the coolant is insufficient as described above, the control unit 500 can maximally increase efficiency in order to prevent the occurrence of the problem due to lack of the coolant by controlling the valve 100 a on the radiator side, the valve 100 b on the heater side, and the valve 100 c on the block side of the integrated thermal management valve 100 to be forcibly open (see FIG. 1 ).

In addition, the control unit 500 can prevent damage to an internal combustion engine by maximally operating a cooling fan (not shown) and operating in a mode in which an output torque of the internal combustion engine is limited to control an increase in the coolant temperature to be suppressed, while recognizing a situation in which the coolant is overheated in advance to transmit this situation to the driver and inducing the driver to check and repair the cooling system before being exposed to a dangerous situation due to lack of the coolant.

FIG. 5 is a view sequentially showing a method of diagnosing lack of the coolant of the vehicle to which the integrated thermal management valve is applied according to another embodiment of the present disclosure.

As shown in FIG. 5 , the method of diagnosing lack of the coolant of the vehicle to which the integrated thermal management valve is applied according to this embodiment will be sequentially described as follows.

First, it is determined whether the valve 100 a on the radiator side of the integrated thermal management valve 100 is open (S100).

In other words, in a state in which the coolant is warmed up and the temperature of the coolant increases to a predetermined temperature or higher, as the integrated thermal management valve 100 controls the valve 100 a on the radiator side to be open, the determination of whether the coolant is insufficient is started.

In other words, in determining whether the coolant is insufficient using the coolant temperature difference between the coolant inlet and outlet of the engine 1, since the coolant temperature difference increases even when the high load operation such as acceleration start-up is performed in which the heat-dissipation amount of the engine increases even when the coolant is not insufficient (see the above-described embodiments), it is preferable that whether the coolant is insufficient is determined using the temperature difference between the block 1 b and the coolant outlet of the engine 1 in a state in which an opening control of the valve 100 a on the radiator side for opening the valve 100 c on the block side is started.

Thereafter, in the state in which the valve 100 a on the outlet side is open (S100), whether an initial condition for determining whether the coolant is insufficient is satisfied is determined by measuring traveling environment information (S200).

The initial condition may include engine RPM information transmitted from an electronic control unit (ECU) of the vehicle, inclination information at which the vehicle is positioned transmitted by a sensor or the like, and outside air temperature information of the vehicle, which is to prevent a problem that an incorrect diagnosis occurs due to the increase in the coolant temperature difference between the coolant inlet and outlet of the engine 1 because an amount of heat transfer of the engine is excessive upon high load uphill traveling in a high temperature area.

When it is determined as being not high load uphill traveling in the high temperature area through the operation S200, the coolant temperature is measured through the coolant temperature sensors 300 and 400 installed on the coolant outlet and the block 1 b of the engine, respectively, and the control unit 500 primarily determines whether the coolant is insufficient by monitoring a decrease amount of the coolant temperature difference, that is, comparing the temperature difference with the set temperature (S300).

In other words, when the coolant is insufficient, referring to “Q=CMAT”, since there is no air on the block 1 b side, a flow rate is relatively increased compared to the head 1 a, and the coolant temperature decreases relatively well in order to preserve an amount of heat, and using this, when the coolant is insufficient, as the valve 100 c on the block side is open, the coolant temperature on the block 1 b side decreases and the coolant temperature on the head 1 a increases. Accordingly, the coolant temperature difference between the block 1 b and the coolant outlet decreases, and when the difference is repeatedly accumulated to a set temperature, that is, 8° C. or less, it may be primarily determined that the coolant is insufficient.

In other words, in this embodiment, when the valve 100 c on the block side is open even upon high load operation, the coolant temperature on the block 1 b side decreases and the coolant temperature on the head 1 a side increases and thus the coolant temperature difference between the block 1 b and the coolant outlet decreases, so that as in the conventional method of diagnosing lack of the coolant, when it is determined whether the coolant is insufficient using the coolant temperature difference between the engine inlet and outlet, it is possible to prevent the problem that the coolant is incorrectly diagnosed as being insufficient by the relatively increased coolant temperature difference between the inlet and the outlet upon high load operation.

As described above, when it is primarily determined that the coolant is insufficient (S300), the control unit 500 calculates the increase amount of the temperature difference between the coolant outlet and the coolant inlet (S400).

In other words, when it is primarily determined that the coolant is insufficient (S300), the control unit 500 calculates the increase amount of the temperature difference between the coolant outlet and the coolant inlet (S400), continuously monitors the increase amount (S500), calculates the accumulated factor value by accumulating the plurality of different factor values for each continuous temperature difference (S600), and finally determines that the coolant is insufficient when it is determined that the factor value is greater than or equal to the comparison value by comparing the accumulated factor value with the set comparison value (S700).

In other words, as a result of continuously monitoring the increase amount of the temperature difference between the coolant outlet and the coolant inlet in the state in which it is primarily determined that the coolant is insufficient, the temperature difference should normally be lower than 10° C., but when the temperature difference is higher than or equal to 10° C., different factor values for each temperature difference calculated as described above, for example, factor values which are 1 when the temperature difference is higher than or equal to 10° C. and 2 when the temperature difference is higher than or equal to 15° C. are accumulated, and at this time, the control unit 500 may finally determine that the coolant is insufficient when it is determined that the accumulated factor value is greater than or equal to the set comparison value.

As a result, in this embodiment, since it is primarily determined whether the coolant is insufficient using the temperature difference detected from the coolant temperature sensors 300 and 400 of the block 1 b and the engine outlet, it is possible to accurately diagnose lack of the coolant by solving the conventional problem that the coolant may be incorrectly diagnosed as being insufficient upon high load operation (acceleration start-up), and in addition, it is possible to improve accuracy in determining whether the coolant is insufficient by finally diagnosing that the coolant is insufficient when the difference is continuously accumulated at a specific temperature or higher using the coolant temperature difference between the engine outlet and the engine inlet.

Meanwhile, when it is finally determined that the coolant is insufficient, the control unit 500 transmits coolant lack information to the driver, and transmits a control signal for proceeding to a fail-safe mode to the integrated thermal management valve 100 (S800).

More specifically, the control unit 500 can maximally increase cooling efficiency in order to prevent the occurrence of the problem due to lack of the coolant by transmitting the control signal for proceeding to the fail-safe mode to the integrated thermal management valve 100 to control the valve 100 a on the radiator side, the valve 100 b on the heater side, and the valve 100 c on the block side of the integrated thermal management valve 100 to be forcibly open.

In addition, the control unit 500 can prevent damage to the internal combustion engine by maximally operating the cooling fan (not shown) and operating in the mode in which the output torque of the internal combustion engine is limited to control the increase in the coolant temperature to be suppressed, while recognizing the situation in which the coolant is overheated in advance to transmit this situation to the driver and inducing the driver to check and repair the cooling system before being exposed to the dangerous situation due to lack of the coolant.

According to the present disclosure, it is possible to improve accuracy in determining whether coolant is insufficient by primarily determining the diagnosis for lack of coolant using the temperature difference between the engine block and the engine outlet detected through three coolant temperature sensors installed on the engine outlet, the engine inlet, and the engine block in order to apply variable split cooling through the integrated thermal management valve (ITM), and finally determining that the coolant is insufficient when the factor in which the difference exceeds the set value using the temperature difference between the engine outlet and the engine inlet at this time is continuously accumulated.

Accordingly, according to the present disclosure, it is possible to prevent damage to the internal combustion engine by recognizing the situation in which the coolant is overheated due to lack of the coolant to transmit the situation to the driver and inducing the driver to check and repair the cooling system before being exposed to the dangerous situation due to lack of the coolant.

In addition, according to the present disclosure, it is possible to maximize the cooling efficiency of the cooling system by maximally operating the cooling fan, while opening all flow paths of the coolant, thereby easily securing the movement distance required for visiting the auto shop for solving the problem of lack of the coolant.

In addition, according to the present disclosure, it is possible to diagnose lack of the coolant using the temperature difference between the engine block and the engine outlet, thereby solving the conventional problem that lack of the coolant is determined using the coolant temperature sensors installed on the engine outlet and the engine inlet, that is, the conventional problem of occurrence of the diagnosis error that it is determined that the coolant is insufficient as the coolant temperature difference between the engine outlet and the engine inlet increases due to the increase in the heat-dissipation amount of the engine.

Although the present disclosure has been described with reference to the embodiment(s) shown in the drawings, this is only illustrative, and various modifications may be made therefrom by those skilled in the art and those skilled in the art will understand that all or part of the above-described embodiment(s) may also be configured by being selectively combined. Accordingly, the true technical scope of the present disclosure should be determined by the technical spirit of the appended claims. 

1. A system for diagnosing lack of coolant, the system comprising: an integrated thermal management valve including a plurality of valves which are openable and closable, and configured to selectively distribute coolant introduced from a head of an engine to front ends of a radiator, a heater, and an oil cooler; a controller configured to receive valve opening and temperature information from the above integrated flow control valve and coolant temperature sensor, and configured to determine whether the coolant is insufficient by monitoring a decrease amount of a coolant temperature difference measured from the block and the coolant outlet as a valve on an outlet side connected to the radiator is open, and finally determine whether the coolant is insufficient by accumulating an increase amount of a temperature difference between the coolant outlet and the coolant inlet; wherein the controller determines that the coolant is insufficient when it is determined that the coolant temperature difference measured from the block and the coolant outlet is lower than or equal to a set temperature. wherein the controller continuously monitors an increase amount of the temperature difference between the coolant outlet and the coolant inlet when it is determined that the coolant is insufficient, and finally determines that the coolant is insufficient when it is determined that an accumulated factor value is greater than or equal to a set comparison value by accumulating different factor values for each continuous temperature difference.
 2. The system of claim 1, wherein the control controller determines whether the coolant is insufficient as a valve on an outlet side connected to the radiator in the integrated thermal management valve is open due to an increase in the coolant temperature.
 3. (canceled)
 4. (canceled)
 5. A method of diagnosing lack of coolant, the method comprising: a first operation of determining whether a valve on a radiator side constituting an integrated thermal management valve is open; a second operation of measuring a coolant temperature through a coolant temperature sensor installed on each of a coolant outlet and a block of an engine as the valve on the outlet side is open; a third operation of determining, by a controller, whether coolant is insufficient by monitoring a decrease amount of a coolant temperature difference measured from the block and the coolant outlet; a forth operation of calculating, by the controller, an increase amount of a temperature difference between the coolant outlet and a coolant inlet when it is determined as a state in which it is determined that the coolant is insufficient; and a fifth operation of accumulating the increase amount of the calculated temperature difference between the coolant outlet and the coolant inlet as a factor value by continuously performing the third operation, and finally determining, by the controller, whether the coolant is insufficient using the accumulated factor value. wherein in the fifth operation, when it is determined that the factor value accumulated through the forth operation is greater than or equal to a set comparison value, it is finally determined that the coolant is insufficient.
 6. The method of claim 5, wherein in the second operation, whether an initial condition for determining whether the coolant is insufficient is satisfied is determined by measuring traveling environment information in the state in which the valve on the outlet side is open before measuring the coolant temperature through the coolant temperature sensor.
 7. The method of claim 6, wherein the initial condition includes RPM information of the engine, inclination information at which a vehicle is positioned, and outside air temperature information of the vehicle.
 8. The method of claim 5, wherein in the third operation, when it is determined that the coolant temperature difference measured from the block and the coolant outlet is lower than or equal to a set temperature, it is primarily determined that the coolant is insufficient.
 9. (canceled)
 10. The method of claim 5, further comprising: a sixth operation of transmitting, by the controller, coolant lack information to a driver when it is finally determined that the coolant is insufficient in the fifth operation, and transmitting a control signal for proceeding to a fail-safe mode to the integrated thermal management valve. 